You cannot do this for here. Here are brief instructions for unsubscribing:
1. click the "unsubscribe" link on the emails of the posts received at the very bottom of the emails.
2. go here > http://wordpress.com/#!/read/edit/ locate and click the "x" next to any blog there to unfollow it and no longer receive posts in the Reader or by email.
3. go to the blog in question and click the unfollow/follow link on your Admin bar.